nAChR elegans

Many techniques for studying functional genomics of important target sites of anthelmintics have been restricted to Caenorhabditis elegans because they have failed when applied to animal parasites. To overcome these limitations, we have focused our research on the human nematode parasite Brugia malayi, which causes elephantiasis. Here, we combine single-cell PCR, whole muscle cell patch clamp, motility phenotyping (Worminator), and dsRNA for RNAi for functional genomic studies that have revealed, in vivo, four different muscle nAChRs ( M-, L-, P-, and N- )...

Ivermectin acts as a positive allosteric modulator of several Cys-loop receptors including the glutamate-gated chloride channels (GluCls), γ-aminobutyric acid receptors (GABAA Rs), glycine receptors (GlyRs), and neuronal α7-nicotinic receptors (α7 nAChRs). The crystal structure of Caenorhabditis elegans GluCl complexed with ivermectin revealed the details of its ivermectin binding site. Although the electron microscopy structure of zebrafish GlyRα1 complexed with ivermectin demonstrated a similar binding orientation, detailed structural information on the ivermectin binding and pore opening for Cys-loop receptors in vertebrates has been elusive...

Nicotine may affect cell function by rearranging protein complexes. We aimed to determine nicotine-induced alterations of protein complexes in Caenorhabditis elegans (C. elegans) cells, thereby revealing links between nicotine exposure and protein complex modulation. We compared the proteomic alterations induced by low and high nicotine concentrations (0.01 mM and 1 mM) with the control (no nicotine) in vivo by using mass spectrometry (MS)-based techniques, specifically the cetyltrimethylammonium bromide (CTAB) discontinuous gel electrophoresis coupled with liquid chromatography (LC)-MS/MS and spectral counting...

Brain function depends on a delicate balance between excitation and inhibition. Similarly, Caenorhabditis elegans motor system function depends on a precise balance between excitation and inhibition, as C. elegans muscles receive both inhibitory, GABAergic and excitatory, cholinergic inputs from motor neurons. Here we show that phosphorylation of the ER-resident chaperone of nicotinic acetylcholine receptors, RIC-3, leads to increased muscle excitability. RIC-3 phosphorylation at Ser-164 depends on opposing functions of the phosphatase calcineurin (TAX-6), and of the casein kinase II homologue KIN-10...

Nicotinic acetylcholine receptors (nAChRs) are essential for cellular communication in higher organisms. Even though a vast pharmacological toolset to study cholinergic systems has been developed, control of endogenous neuronal nAChRs with high spatiotemporal precision has been lacking. To address this issue, we have generated photoswitchable nAChR agonists and re-evaluated the known photochromic ligand, BisQ. Using electrophysiology, we found that one of our new compounds, AzoCholine, is an excellent photoswitchable agonist for neuronal α7 nAChRs, whereas BisQ was confirmed to be an agonist for the muscle-type nAChR...

The cholinergic class of anthelmintic drugs is used for the control of parasitic nematodes. One of this class of drugs, tribendimidine (a symmetrical diamidine derivative, of amidantel), was developed in China for use in humans in the mid-1980s. It has a broader-spectrum anthelmintic action against soil-transmitted helminthiasis than other cholinergic anthelmintics, and is effective against hookworm, pinworms, roundworms, and Strongyloides and flatworm of humans. Although molecular studies on C. elegans suggest that tribendimidine is a cholinergic agonist that is selective for the same nematode muscle nAChR as levamisole, no direct electrophysiological observations in nematode parasites have been made to test this hypothesis...

Nicotine, the major psychoactive compound in tobacco, targets nicotinic acetylcholine receptors (nAChRs) and results in drug dependence. The nematode Caenorhabditis elegans' (C. elegans) genome encodes conserved and extensive nicotinic receptor subunits, representing a useful system to investigate nicotine-induced nAChR expressions in the context of drug dependence. However, the in vivo expression pattern of nAChR genes under chronic nicotine exposure has not been fully investigated. To define the role of nAChR genes involved in nicotine-induced locomotion changes and the development of tolerance to these effects, we characterized the locomotion behavior combining the use of two systems: the Worm Tracker hardware and the WormLab software...

Understanding the genes and mechanisms involved in acute alcohol responses has the potential to allow us to predict an individual's predisposition to developing an alcohol use disorder. To better understand the molecular pathways involved in the activating effects of alcohol and the acute functional tolerance that can develop to such effects, we characterized a novel ethanol-induced hypercontraction response displayed by Caenorhabditis elegans. We compared body size of animals prior to and during ethanol treatment and showed that acute exposure to ethanol produced a concentration-dependent decrease in size followed by recovery to their untreated size by 40 min despite continuous treatment...

Polymodal nociceptors sense and integrate information on injurious mechanical, thermal, and chemical stimuli. Chemical signals either activate nociceptors or modulate their responses to other stimuli. One chemical known to activate or modulate responses of nociceptors is acetylcholine (ACh). Across evolution nociceptors express subunits of the nicotinic acetylcholine receptor (nAChR) family, a family of ACh-gated ion channels. The roles of ACh and nAChRs in nociceptor function are, however, poorly understood...

Ticks and tick-borne diseases have a major impact on human and animal health worldwide. Current control strategies rely heavily on the use of chemical acaricides, most of which target the CNS and with increasing resistance, new drugs are urgently needed. Nicotinic acetylcholine receptors (nAChRs) are targets of highly successful insecticides. We isolated a full-length nAChR α subunit from a normalised cDNA library from the synganglion (brain) of the brown dog tick, Rhipicephalus sanguineus. Phylogenetic analysis has shown this R...

Nicotinic acetylcholine receptors (nAChR) are members of the Cys-loop ligand-gated ion channel superfamily. Muscle nAChR are heteropentamers that assemble from two α, and one each of β, γ, and δ subunits. Each subunit is composed of three domains, extracellular, transmembrane and intracellular. The transmembrane domain consists of four α-helical segments (M1-M4). Pioneering structural information was obtained using electronmicroscopy of Torpedo nAChR. The recently solved X-ray structure of the first eukaryotic Cys-loop receptor, a truncated (intracellular domain missing) glutamate-gated chloride channel α (GluClα) showed the same overall architecture...

Nicotinic acetylcholine receptors (nAChRs) play a key role in the normal physiology of nematodes and provide an established target site for anthelmintics. The free-living nematode, Caenorhabditis elegans, has a large number of nAChR subunit genes in its genome and so provides an experimental model for testing novel anthelmintics which act at these sites. However, many parasitic nematodes lack specific genes present in C. elegans, and so care is required in extrapolating from studies using C. elegans to the situation in other nematodes...

We report a genome-wide RNA interference (RNAi) screen for Suppressors of Clozapine-induced Larval Arrest (scla genes) in Caenorhabditis elegans, the first genetic suppressor screen for antipsychotic drug (APD) targets in an animal. The screen identifies 40 suppressors, including the α-like nicotinic acetylcholine receptor (nAChR) homolog acr-7. We validate the requirement for acr-7 by showing that acr-7 knockout suppresses clozapine-induced larval arrest and that expression of a full-length translational GFP fusion construct rescues this phenotype...

High levels of resistance to spinosad, a macrocyclic lactone insecticide, have been reported previously in western flower thrips, Frankliniella occidentalis, an economically important insect pest of vegetables, fruit and ornamental crops. We have cloned the nicotinic acetylcholine receptor (nAChR) α6 subunit from F. occidentalis (Foα6) and compared the nucleotide sequence of Foα6 from susceptible and spinosad-resistant insect populations (MLFOM and R1S respectively). A single nucleotide change has been identified in Foα6, resulting in the replacement of a glycine (G) residue in susceptible insects with a glutamic acid (E) in resistant insects...

RIC-3 enhances the functional expression of certain nicotinic acetylcholine receptors (nAChRs) in vertebrates and invertebrates and increases the availability of functional receptors in cultured cells and Xenopus laevis oocytes. Maximal activity of RIC-3 may be cell-type dependent, so neither mammalian nor invertebrate proteins is optimal in amphibian oocytes. We cloned the X. laevis ric-3 cDNA and tested the frog protein in oocyte expression studies. X. laevis RIC-3 shares 52% amino acid identity with human RIC-3 and only 17% with that of Caenorhabditis elegans...

The free-living nematode Caenorhabditis elegans is a useful model for studying the pharmacology of anthelmintics. Currently approved anthelmintics have various mechanisms of action, including activity at nematode nicotinic acetylcholine receptors (nAChRs). Classical anthelmintic agonists of these receptors (nicotine, levamisole, pyrantel and bephenium) caused intact specimens of C. elegans to undergo contracted paralysis. The nAChR antagonist mecamylamine paralysed intact worms and blocked the actions of the agonists...

BACKGROUND: Our previous work indicated that novel analogs of choline have cytoprotective effects in vitro that might be useful in neurodegenerative conditions such as Alzheimer's disease (AD). Furthermore, two lead compounds (JWB1-84-1 and JAY2-22-33) from a library of more than 50 improved cognitive performances in a transgenic mouse model of AD. The purpose of these experiments was to more specifically investigate the neuroprotective capabilities of these lead compounds both in vitro and in vivo...

The nematode Caenorhabditis elegans is an established model organism for studying neurobiology. UNC-63 is a C. elegans nicotinic acetylcholine receptor (nAChR) α-subunit. It is an essential component of the levamisole-sensitive muscle nAChR (L-nAChR) and therefore plays an important role in cholinergic transmission at the nematode neuromuscular junction. Here, we show that worms with the unc-63(x26) allele, with its αC151Y mutation disrupting the Cys-loop, have deficient muscle function reflected by impaired swimming (thrashing)...

Inappropriate or excessive activation of ionotropic receptors can have dramatic consequences for neuronal function and, in many instances, leads to cell death. In Caenorhabditis elegans, nicotinic acetylcholine receptor (nAChR) subunits are highly expressed in a neural circuit that controls movement. Here, we show that heteromeric nAChRs containing the acr-2 subunit are diffusely localized in the processes of excitatory motor neurons and act to modulate motor neuron activity. Excessive signaling through these receptors leads to cell-autonomous degeneration of cholinergic motor neurons and paralysis...

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that mediate fast synaptic transmission in the insect nervous system and are targets of a major group of insecticides, the neonicotinoids. They consist of five subunits arranged around a central ion channeL Since the subunit composition determines the functional and pharmacological properties of the receptor the presence of nAChR families comprising several subunit-encodinggenes provides a molecular basis for broad functional diversity...